Replaceable leader pin bushing



June 9, 1956 K. JANISZEWSKI REPLACEABLE LEADER PIN BUSHING Filed Sept. 12, 1950 5 2 M w H 9 m m M x w u ,m

W M H r g 4 a 25 a llllw vl/ M M w. II M Y E G 2,751,260 REPLACEABLE LEADER PIN BUSHING Kasimir Janiszewski, Milwaukee, Wis. Application September 12, 1950, Serial No. 184,366 9 Claims. (Cl. 308-4) This invention relates to improvements in replaceable leader pin bushings.

The invention consists in substituting for conventional leader pin bushings an easily replaceable bushing which is seated in such a manner to be accurately aligned with the pin and to maintain such alignment during die set operation.

In conventional die sets comprising a punch holder mounted for reciprocable movement toward and from a die shoe, it is of the utmost importance that the reciprocable movement of the die parts be accurately guided so that the punch holder will not deviate laterally; otherwise the work being formed between the die parts will be subject to alignment inaccuracies with resultant lowering of the quality of work produced. For the purpose of guiding the reciprocating movement of the punch holder, the die shoe is conventionally provided with several upstanding leader pins which are telescopically receivable within punch holder bushings seated in suitable through apertures in the punch holder.

Heretofore it has been the practice to press fit the punch holder bushings in their seats. The internal stresses in the bushing by this practice tend to distort the accurately machined form of the bushing, and it has been a routine necessity to relap the bushing bore to correct the axial alignment of the bushings and leader pins. In some extreme cases the bushing bore axis was laterally displaced to such an extent as to make it advisable to rebore the punch holder apertures and insert oversized bushmgs.

It is the principal object of this invention to provide a replaceable leader pin bushing which need not be seated in the punch holder aperture with a press fit, but which may be merely hand or tap fitted into its seat. Consequently no distortion of the leader pin bushing wall occurs and it is possible to accurately machine and lap the bushing bore prior to seating with no further lapping being necessary after the bushing is in place. Furthermore the removal of the bushing from its hand pressed position becomes a simple matter and the bushing may be easily replaced When worn.

It is a further object of the invention to provide a tap fitted punch holder bushing with means external of the inner walls of the punch holder aperture, and independent of bushing wall resiliency, for securely positioning the bushing in axial alignment with the leader pin.

In this connection it is an object of the invention to provide a bushing which comprises a bearing sleeve having an external collar providing a shoulder intermediate the sleeve end margins which is abuttable in stabilizing fixed position against the under surface of the punch holder and which is provided with means for fastening said collar and punch holder into a unitary structure.

Another object of the invention is to laterally offset the punch holder connected portion of the collar from the sleeve to utilize collar resiliency whereby the exposed portion of the bushing is yieldable laterally for shock absorbing and self realignment purposes.

Another object of the invention is to fabricate the sleeve and collar from oppositely seamed rolled sheets to strengthen the complete unitary bushing.

Other objects will be more apparent to one skilled in 0 the art upon an examination of the following disclosure. 7

In the drawings:

2,751,2fiil Patented June 19, 1956 Fig. l is a side elevational view of an assembled die set embodying the present invention with portions adjacent one of the leader pins being shown in cross section.

Fig. 2 is a cross sectional view taken along the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary cross sectional view of the punch holder showing the details of a modification of the bushing.

Fig. 4 is a fragmentary cross section of the punch holder showing a further modification of the bushing.

Fig. 5 is a bottom view of the structure shown in Fig. 4.

Fig. 6 is a cross sectional view of a modification of the bushing showing the collar in the shape of a frustrum of a right cone with an annular space between the bushing sleeve and collar.

Fig. 7 is a bottom view of the bushing shown in Fig. 6.

Fig. 8 is a fragmentary view of a modification of the mounting of the bushing shown in Fig. 6.

The die set comprises spaced platens conventionally referred to as a die shoe 10 and a punch holder 11. The punch holder is mounted for reciprocal movement toward and from the die shoe 10. The movement of the punch holder is guided in its reciprocation and against deviation by a leader pin 12 which is securely mounted in upstanding position in a mounting insert 13. The leader pin and mount as illustrated have complementary mating tapers which comprise the claimed subject matter of a companion application for patent entitled Tapered Leader Pin and Die Shoe Bushing Assembly executed of even date herewith.

The punch holder 11 is provided with several through apertures 14 which provide seats for the bushing sleeves 16. The bushing sleeves 16 are axially aligned with the leader pins 12 and provide a bearing surface or bore 17 in which the pin is telescopically receivable to guide the punch holder.

Sleeve 16 is intended to be tap or hand pressed into seated position in the bore 14 and for this purpose is made of but slightly larger external diameter than the internal diameter of bore 14. The difference in diameters is desirably in the range of five ten thousandths of an inch. Accordingly, some slight pressure is required to seat the sleeve into the bore. This difference in diameter is very much less than that required heretofore for a press fit, the difference for a press fit is conventionally in the range of twenty-five. ten thousandths of an inch. The requirement of a hand or tap fit facilitates the assembly of the bushing and punch holder and axial alignment of the sleeve with the pin is assured.

The inner bearing surface 17 of the sleeve 16 is accurately machined and lapped to perfect sliding fit and alignment with the leader pin 12 prior to seating the sleeve within the punch holder apertures. The tap or hand fit of the sleeve does not distort the bearing Walls 17 of the sleeve, as is sometimes the result of a press fit; consequently such surfaces do not require relapping after seatmg.

In order to securely mount the sleeve in the punch holder, the bushing sleeve is made of such a length that when properly seated a portion of the sleeve will extend below the squared under surface 20 of the punch holder 11. The rigid positioning of the sleeve 16 in its punch 'holder seat 14 is accomplished by means of a collar 21 (Figs. 1 and 2) which is fixed by welding or the like to provided.

=end marginot sleeve .16. Shoulder, of collar 724, which comprises the lower -base -of the cone frustrum, is consequently laterally ofiset from the outer periphery of the sleeve 1,6, thus forming an annular tapered space, indicated as .28, between thersleeve and collar. Flhe collar .is preferably made of resilient metal. Accordingly, the portion of the :sleeve below the confines-of the punch ":holder 11 is provided with;a-iresi.liently Yielding lateral pp rt which will yield s ightly up lateral shock and return the sleeve to proper axial alignment thereafter.

The bushing may rhe relatively-rrigidly securedin its :axiallyaligned 1 seated position by holding ithecollar tight against the undersurfaceofrthePunch holderin a variety of fashions. As :best shown-.infigs. 6;and 7 the-collar .may:be tack weldedatSl to the punch holder. As in .Fig. 8 the collars-may alternatively .be :provided with peripherally spaced ,monntingqearsjifi which register ,with punch holder jtaps 34:to-;rec eiv e bolts. 33 which draw the ,shoulder 27 ofthecollarfirnilyagainst,the;squaredrunder surface .of the :punch holder.

.In the embodiment shown injFigs. :1: to ;the;-collar is provided'with a seriesof;arcuately'spacedttransversegaper- ;turesor sockets 35,.into--.which fingered portions of arms 36 (Fig. '4) or :39 ,(Fig. -l);extend. The opposite ends of the arms may be either bolted, as shownyati 37 of Fig.

punch :holder. Any desired number ;of collarrsockets and arms may be: provided. As;.shown-:in :Fig.-2 two diametrically oppositely disposedarms and sockets-are In Fig. 5 three :arms z-and: sockets, are shown mutually spaced at 120 angles.

The exact shape; of the :arrns 3.6 :andy39isibroadly' immaterial; a double fingered arm 46 is:shown in Fig. 3

and single'fingerarmsi36- and-39 areshowniin Figs. .1

and 4. If desired the material :of nvhichrthearmsiare made'may be of relatively soft metal to permita-screw driver blade to be 'insertedfbet-weenlhe arm and collar to pry thefingersfrom thecollarasockets iwithoutrbreaking thetachwelds. Thexbushingmay then =be-removed and a new bushing inserted randithei'fingers inserted in the respective :sockets-zofathe-new bushings -:.t o bring the collar shoulder up tight againstithepuncnholder.

'gThe bushings may be; removed: trom their.iseatssforvreplacement or the like simply by loosening::the"'-bolts-1and tapping the'sleeves downwardlyrfrom its seat. :Whenthe arms are tack welded, -ithe-swelds .:may be broken :by. .a sharp blow on'the upper :end margin of the sleeveszto 'force the sleevesfrom theirrseats.

If desired the'bearing-surface may be lubricated by providing the collar with an oil-reservoir formed between diametricallyopposite-each other -in the assembled collar and sleeve. This'construction is best shoWn in' FigR7. in this manner internal stresses tending 'to-deform-"the bearing surfaces-balance each other-and misalignment of the leaderpin and sleeve axis is prevented.

From (the foregoingdescription, }it is 1 evident that: by providing the bushin g sleeyes with the shouldered collajrs Cir l only a tap fit need be employed to seat and align the sleeve axially with the leader pin thus eliminating press fit distortion of the bushing. As a result, bearing surfaces can be lapped prior to assembly with the assurance that they will remain accurate when seated. Furthermore the specific arrangement in Fig. .6, wherein the shouldered portion of the collar is offset laterally from the outer sleeve periphery, accentuates the resilient spring characteristic of=the collar and enables the bushing =to absorb lateral shock without misalignment. The bushings are easily removed with hand tools Without damage to .theepunch holder-seats and areplacement bushingmay be reinserted in the same seat without'it being necessary to ;drill new holes to receive oversized bushings.

1=I.cla im:

.l. The combination with. a die set platen having an .apertureanda bushing in said'aperturetsaid bushingcomprising a sleeve having an extension beyond said-platen, :ot a collarcomprisinga cylindrical wallcoeaxialwithithe sleeve extension and connected thereto, one endnnargin ofzthecollancornprising ashoulder for abutment against :the platemsaid collar. being providediwith exposed sockets, :andarms engagedin said sockets, said arms having means .radiallyspacedfrom said collar .-for.mounting said-arms ztortheplaten:wherebythe collar .and sleeve extensioncare :free--for:lirnitedlateral yielding within said-space.

:2. The combination with .a die set .platen having :a face, an aperture, :and a bushing :in .the .1aperture,= said :bushing. comprisinga sleeve having .an ,extension ,beyond .said platen :face, ofa collar. comprising a wall coeaxial with and enclosing the sleeve extension, one :endzofihe :collar being aconnected to .the ,-end not .the sleevewextension and the other end of the-collar constituting-a .shoulder in. abutment against the ;plateniface, and means .connected with :the collar and :rigidly :united with :the faceaof: the: platen for connecting saidcollar to the platen.

,3. {Ehe .devicezofuclaim 2 in whichgthe collar is pro- .vided .withan annular chamber .,;constituting an oiltreservoir, said rsleeveihaving 1 a duct leading therefromrto the interior rot the sleeve.

4. The device of claim 2 in which the connecting means-comprises'arms, thecollanhaving laterally open sockets ;in which the :arms are engaged, and itheszarms -having meansradially spaced from the collar for rigidly connectingthe arrns to the platen.

5. Thedevice. of, claim 2in,-which-the;Wall of-the eollar gis at ,itsouter 56nd, the inner end margin -,of ;the coll ar be ng :'0 se :a ia 1y .f t -s ve the coll r-portion inte med at :said n pr i i resilient uppo t Q .saidsl w :d ic .10 laim 21i which -.-th sl v -52n collar comprise tubes having axial-seamsin diametrieally pnos t rpos icns- 7.-Tl he device of claim '2 in which the connecting means includes ,aweld to: said face.

{file gdeyiee of claim '2 r in which ,the connecting means -;ing ludes ,a plurality of screws threaded-into the platen through; said face.

59. The -device of-claim -2 in which the sleeve com- ;pr ises a leader pin-,hushinghaving-a relatively loose, fit. in id ai -;-r ate ap r na dep n e o p si omv ;said -.collar an d.said connecting means, the rigid nion 1 of the latter -to, theplaten tacebeing-oiiset radially rpm the bushing and substantially symmetricalabout thebushing, sleeye, .whereby toposition the sleeve accurately sand .with a. degree of resilience I between the, sleeve. .and the rigid union ,to. the ;,platen.

References. Cited in the'file of thispatent l UNITED -STATES PATENTS 2,013,488 Carrier Sept. 3,,1935 2,238,302 Baumbach Apr.i 1S, 1941 2,356,3 7 ,Danneman Y Aug. 22, 194 2,445,574 Grunow July 20,1948 

